20866247 has 4 divisors (see below), whose sum is σ = 21152160. Its totient is φ = 20580336.

The previous prime is 20866231. The next prime is 20866249. The reversal of 20866247 is 74266802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74266802 = 2 ⋅37133401.

It is a cyclic number.

It is not a de Polignac number, because 20866247 - 2⁴ = 20866231 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20866249) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 142847 + ... + 142992.

It is an arithmetic number, because the mean of its divisors is an integer number (5288040).

Almost surely, 2^20866247 is an apocalyptic number.

20866247 is a deficient number, since it is larger than the sum of its proper divisors (285913).

20866247 is an equidigital number, since it uses as much as digits as its factorization.

20866247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285912.

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 20866247 is about 4567.9587344896. The cubic root of 20866247 is about 275.3054325424.

The spelling of 20866247 in words is "twenty million, eight hundred sixty-six thousand, two hundred forty-seven".